Instafilter\Filter::_exec PHP Method

    private function _exec($program, $params, $passthru = false)
    {
        //  Determine the path
        $this->im_path = realpath($this->configuration['imagemagick_dir'] . $program);
        // store the filename for this image
        $filename = $this->imagick()->getImageFilename();
        // check imagemagick is where we expect it
        if (!$this->im_path) {
            $this->im_path = realpath($this->configuration['imagemagick_dir'] . $program . '.exe');
        }
        if (!$this->im_path) {
            throw new \RuntimeException("imagemagick executables not found in " . $this->configuration['imagemagick_dir']);
        }
        // save the filters that have already been applied
        $this->imagick()->writeImage($filename);
        $command = $this->im_path . " " . $params;
        $code = 0;
        $output = null;
        //do the actual command
        $passthru ? passthru($command) : exec($command, $output, $code);
        // reload the imagemagick instance once the manual command is done
        $this->image->imagick(new \Imagick($filename));
        // check if it's successful
        if ($code != 0) {
            throw new \Exception("imagemagick failed to edit the image. Returned with {$code}.<br /><br />Command:\n <code>{$command}</code>");
        }
        return $output;
    }